1. Technical Field
The present disclosure relates to memory devices, and, more particularly, to semiconductor memory devices that internally control an interfacing environment and memory systems including the memory devices.
2. Discussion of the Related Art
Various types of memory devices have been developed to realize high storage capacity in a small size. Recently, non-volatile memory devices such as flash memory devices are being widely used, even in large and complicated electronic systems such as factory automation systems and intelligent building systems. However, the flash memory devices may not be easily controlled when a proper operating system is not available in the electronic systems that employ the flash memory devices. Thus, various memory devices capable of providing a vendor of the flash memory devices with convenient interfaces have been developed and are broadly employed in the electronic systems. The various memory devices include multi-media cards (MMCs), secure digital (SD) cards, xD cards, and the like, which may be used to provide a relatively simple interface.
Interface environments can have various parameters, such as clock frequencies and impedance differences, which may cause mismatches between the memory devices and the host. Impedance mismatches, for example, can cause reflections of signals from memory devices acting as a load when signals are transmitted from the host, particularly, as operating frequencies increase.
Such mismatches of the interface environments may even cause the host to not recognize the memory devices. Further, increasing demand for high speed data transmission may increase the failure or malfunction of the memory devices.